Study on the Detection of Soil Water Content Based on the Pulsed Acoustic Wave (PAW) Method

The primary objective of this work was the utilization of the pulsed acoustic wave (PAW) method to explore the feasibility of measuring soil water content (SWC) based on the soil acoustic parameter acquisition (SAPA) system. Acoustic parameters (pulse acoustic velocity and acoustic attenuation coefficient) were collected from paddy soil (clay), red soil (loam), and lateritic-red soil (clay loam) under different SWCs. The calibration models of the pulse acoustic velocity, the attenuation coefficient, and the double acoustic parameters with the soil volumetric water content (SVWC) were established through fitting analysis. We studied the repeatability and reproducibility of the calibration models and conducted an extensive field experiment for 40 days to evaluate the calibration model's ability to predict SVWC. The results showed that the repeatability and reproducibility of the SVWC calibration model based on pulse acoustic velocity were the best, which showed that the acoustic velocity was more suitable for the inversion of SVWC than the acoustic attenuation coefficient. The 40-day field study's experimental results also verified the potential value of pulse acoustic velocity in SVWC detection.